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<p>Small hydroelectric power plants (SHPs) can significantly impact aquatic ecosystems by altering hydrological regimes and ecological interactions. Analyzing food networks is a valuable tool for understanding how biological communities interact and for assessing the ecological consequences of such disturbances. This study evaluated the structure of fish trophic interaction networks upstream and downstream of an SHP in Brazil. Fish were sampled quarterly from March 2013 to December 2014 at two points in each stretch. Gastrointestinal contents were analyzed, and network metrics, including connectance, modularity, nestedness, specialization, extinction, and robustness, were calculated. Permutation tests and linear mixed-effects models were used to assess differences between stretches. Results showed downstream networks were more sensitive in most metrics, with higher connectivity and nestedness, but lower modularity and specialization. A higher extinction rate upstream may indicate greater dependence on specific resources, while higher robustness downstream suggests functional redundancy, where species can compensate for each other’s loss. Despite lower specialization, downstream communities maintain functionality. These results underscore the need to include trophic interaction analyses in environmental assessments to better understand and mitigate the ecological effects of river fragmentation caused by SHPs.</p>

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Effects of a small reservoir on the trophic network structure of fishes: a comparison between downstream and upstream stretches

  • 期刊论文

  • 发表日期：

    2025年5月29日

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  • Thiago Deruza Garcia,
  • Rosemara Fugi,
  • Augusto Seawright Zanatta,
  • Dhiego Gomes Ferreira,
  • José Luís Olivan Birindelli,
  • Ana Paula Vidotto-Magnoni

摘要

Small hydroelectric power plants (SHPs) can significantly impact aquatic ecosystems by altering hydrological regimes and ecological interactions. Analyzing food networks is a valuable tool for understanding how biological communities interact and for assessing the ecological consequences of such disturbances. This study evaluated the structure of fish trophic interaction networks upstream and downstream of an SHP in Brazil. Fish were sampled quarterly from March 2013 to December 2014 at two points in each stretch. Gastrointestinal contents were analyzed, and network metrics, including connectance, modularity, nestedness, specialization, extinction, and robustness, were calculated. Permutation tests and linear mixed-effects models were used to assess differences between stretches. Results showed downstream networks were more sensitive in most metrics, with higher connectivity and nestedness, but lower modularity and specialization. A higher extinction rate upstream may indicate greater dependence on specific resources, while higher robustness downstream suggests functional redundancy, where species can compensate for each other’s loss. Despite lower specialization, downstream communities maintain functionality. These results underscore the need to include trophic interaction analyses in environmental assessments to better understand and mitigate the ecological effects of river fragmentation caused by SHPs.